By RB's method, my pipe is 93mm. It's probably killing my bottom end. Does anyone make single chamber pipes anymore? My OS is on a Paris ribbed pipe and screams. I went to the one piece baffled RD because my pipe kept disconnecting from the manifold. But, I did not notice any performance difference from the change from the Paris to the RD. I measured the distance from the end of the baffle to the manifold end of the muffler and it is 115 mm. It is a cone baffle. Is the Novamega and RB a cone baffle?

My engine has only one, thick shim. Took it out without clearance problems. A hint better bottom end. I need to retune the bottom end, it will die at idle every so often.